The rpath on linux was not set to include the nuodb/lib64 directory; fix
this for linux and solaris so that proper rpath entries are present, e.g:

readelf --dynamic /var/lib/gems/1.9.1/gems/nuodb-1.0.1/lib/nuodb/nuodb.so
 ...
 0x000000000000000f (RPATH)  Library rpath: [$ORIGIN:/opt/nuodb/lib64]
 ...